Just in the United States, more than 80 million people invest and speculate in the shares of thousands of publicly traded companies and in many other financial instruments. The day to day price of a given instrument is essentially a manifestation of the investors' (or sellers, brokers, advisors and other market participants') confidence in the future financial performance of a company or the price of a commodity.
Equity investors obtain some information directly from the listed corporations, perhaps through corporate websites, conference calls or mail. However, tight regulatory restrictions regarding shareholder communication and the obvious need for unbiased opinion mean that investors rely chiefly on indirect channels, principally financial analysts and media.
Analysts employ numerically based models of the commodities or businesses they track, including the associated industry and economic parameters. They must weigh up different factors, pulling in different directions, to arrive at buy/sell recommendations and price targets/fair price estimates.